Field of the Invention
The disclosure generally relates to an antenna structure, and more particularly, to an antenna structure for reducing an SAR (Specific Absorption Rate).
Description of the Related Art
With advancements in mobile communication technology, mobile devices such as portable computers, mobile phones, multimedia players, and other hybrid functional portable electronic devices have become more common. To satisfy user demand, mobile devices can usually perform wireless communication functions. Some devices cover a large wireless communication area; these include mobile phones using 2G, 3G, and LTE (Long Term Evolution) systems and using frequency bands of 700 MHz, 850 MHz, 900 MHz, 1800 MHz, 1900 MHz, 2100 MHz, 2300 MHz, and 2500 MHz. Some devices cover a small wireless communication area; these include mobile phones using Wi-Fi and Bluetooth systems and using frequency bands of 2.4 GHz, 5.2 GHz, and 5.8 GHz.
An antenna is indispensable in a mobile device supporting wireless communication. To prevent electromagnetic waves transmitted by an antenna from negatively affecting the human body, the SAR (Specific Absorption Rate) of a mobile device is prescribed and limited by law. It becomes a critical challenge for current designers to design an antenna element which has good communication quality and meets the requirements of the law.